1. Field of the Invention
The present invention relates to a valve device and to a method for avoiding explosion propagation in conduits or for limiting the consequences of explosion propagation in conduits.
2. Description of Related Art
In existing systems with conduits connected to volumes in which there is explosion hazard, either mechanical shut-off valves or chemical shut-off valves are used, or a mechanical valve is provided at a distance downstream of a chemical barrier. Chemical devices have the drawback of requiring a relatively large amount of extinguishing agent, particularly for conduits with a large diameter, and that the extinguishing agent is exhausted relatively quickly. Mechanical devices have the drawback that they are either not completely sealed as a result of for instance seals which do not fit perfectly between the closing body and the passage and/or an inadequate locking of the closing body in the housing, or that they are highly complex and expensive.
WO 87/03210 describes a device for eliminating fire risks resulting from the presence of glowing particles in a pipeline. An extinguishing agent is injected for this purpose via a line which debouches in the vicinity of the valve body. In such systems the glowing particles move at a process speed of typically 21 m/s. Such devices operate preventively and are intended for the purpose of avoiding explosion hazard, i.e. to ensure that no explosions occur. Such a device is not intended and not suitable for the purpose of preventing explosion propagation in conduits, since an explosion advances at a speed which is more than 10 times greater than that of glowing particles. The explosion propagation speed is typically around 300 m/s. The present invention relates to taking so-called curative, post-explosion measures which must ensure that a pressure wave front cannot advance in the conduit.
Embodiments of the present invention have the object of obviating these drawbacks by providing a valve device and method which are simple but nevertheless guarantee that explosion propagation is prevented in reliable manner.